Hey friend! Have fun exploring Q&A, but in order to ask your own
questions, comment, or give thumbs up, you need to be logged in to your
Moz Pro account.
You can also earn access by receiving 500
MozPoints
from participating in YouMoz and the Moz Blog!

This is an area where I'm not too familiar. I would post a new question and give describe in length what is going on. Do my steps first and if you don't get all of them cleared up then post new question and have a server guy help you. Good Luck!

Only bad if those 404 pages are resulting from pages in your own site. ( For example, the page that has the 404 is being linked to by another page on yoru site) Not from external sites. That being said, fix them. It's easy. If the page actually doesn't exist then remove them from your sitemap and them remove url like I mentioned before. If the page exists (like example.com/page but the 404 is for example.com/page.html) you can 301 pages or fix your site extensions. I know Joomla has a SEF URL setting.

A Soft 404 generally means that someone has requested a page that wasn't found by Google. You might want to "Fetch as Google" to find any pages that are being linked to that do not exist. (Go into WMT and under that specific URL, under "Health", select "Fetch as Google") This should give you a list of all the URLs that are returning a 404 or other errors. If you have already done this, make sure that the pages that are showing up in your errors are not still included in your sitemap. (remove them if they are and then remove the URLs from Google by going to Optimization and Remove URLs) You should also make sure that the "preferred URL" has been selected for your site. If you use the www version of your site and the non www has the errors (or vise versa) then this could be the problem too. (You'll have to confirm both versions of your site and then go into configuration, settings then preferred domain). I gave you a lot of work here but these should solve the problem. If not, post any feedback and any solutions you worked on.

Hey friend! Have fun exploring Q&A, but in order to ask your own
questions, comment, or give thumbs up, you need to be logged in to your
Moz Pro account.
You can also earn access by receiving 500
MozPoints
from participating in YouMoz and the Moz Blog!
Learn more.